Prosthetic devices have enabled amputees to regain mobility impaired by loss of a limb, to participate again in activities enjoyed before such a loss, and to participate in new activities for the first time. Moreover, with amputees fully engaging in today's active lifestyles, amputees are participating in events such as marathons, basketball, and free-style downhill skiing.
The stump of an amputee's limb is typically placed in a socket having an inter contour that conforms to the shape of the stump. A fitting mounted on the lower end of the socket is then attached to the upper end of an elongated prosthetic pylon. Finally, a prosthetic foot is bolted to the lower end of the pylon. The pylon thus serves as the structural member used to interconnect the limb socket and the prosthetic foot. Conventional prosthetic pylons have generally been constant heavy walled tubes or cylinders manufactured from either aluminum, which is quite stiff, or nylon, which is heavy and exhibits excessive flex under high loading conditions.
In order to increase the strength and reduce the weight of conventional pylons, tubular resin-impregnated fiber reinforced composite pylons have been developed. These composite pylons can be trimmed easily to any length depending upon the desired distance between the socket fitting and the prosthetic foot. However, tubular pylons, whether they are made of composite or any other material, still exhibit the disadvantage of having flex characteristics that are dependent on finished length. In other words, a shorter pylon with the same construction as a longer pylon will possess a stiffer flex characteristic than its longer counterpart. Prosthetic pylons could be manufactured in a range of wall thicknesses depending on their length to provide uniform flexure characteristics regardless of pylon length. However, tubular prosthetic pylons are typically trimmed in the field by a prosthetist during the fitting of a prosthesis on an amputee. Manufacturing pylons having different wall thicknesses or different flex characteristics for different lengths would require the prosthetist to maintain a large inventory of prosthetic pylons so that a wide variety of pylon lengths were on hand for use.